Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

Rare earth element sintered magnet and method for producing rare earth element sintered magnet

a technology of rare earth elements and sintered magnets, which is applied in the direction of magnetic materials, solid state diffusion coatings, magnetic bodies, etc., can solve the problems of affecting the use of magnet materials in such an atmosphere, prone to chipping when handled, and deterioration, cracking or cracking of magnet materials,

Active Publication Date: 2008-10-21
SHIN ETSU CHEM IND CO LTD
View PDF32 Cites 7 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention provides rare-earth sintered magnets and methods of manufacture that do not suffer from hydrogen embrittlement in a high-pressure hydrogen atmosphere. The method involves surface machining the magnet, metal plating the surface, and heat treatment to form a layer of excellent hydrogen resistance on the surface. The resulting magnets have improved resistance to damage from chipping and are suitable for use in devices exposed to hydrogen for long periods of time. The invention also provides a method of manufacturing rare-earth sintered magnets that does not require a high-temperature heat treatment.

Problems solved by technology

However, because the Sm2Co17-based magnet and the microdispersed Sm2O3-containing layer of cobalt and / or cobalt and iron are hard and fragile, they tend to chip when handled, such as during product assembly.
Therefore, in hydrogen atmospheres at pressures higher than 1 MPa, hydrogen embrittlement occurs, leading to breaking, cracking or degradation of the magnet material.
Use in such an atmosphere is thus impossible.
The cause of the above problem is the low mechanical strength of Sm2Co17-based magnets.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Rare earth element sintered magnet and method for producing rare earth element sintered magnet
  • Rare earth element sintered magnet and method for producing rare earth element sintered magnet
  • Rare earth element sintered magnet and method for producing rare earth element sintered magnet

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0044]A Sm2Co17-based magnet alloy was produced by formulating a starting material containing 25.0 wt % of samarium, 17.0 wt % iron, 4.5 wt % of copper and 2.5 wt % of zirconium, with the balance being cobalt. The starting material was placed in an alumina crucible and melted in an induction melting furnace under an argon atmosphere, then cast in a mold.

[0045]The resulting Sm2Co17-based magnet alloy was reduced to a size of about 500 μm or less with a jaw crusher and a Braun mill, after which it was milled to an average particle size of about 5 μm with a jet mill using a stream of nitrogen. The milled powder was molded with a magnetic field-generating press under a pressure of 1.5 t / cm2 within a magnetic field of 15 kOe. The resulting powder compacts were sintered in a heat treatment furnace under an argon atmosphere at 1190° C. for 2 hours, then solution-treated in argon at 1175° C. for 1 hour. Following the completion of solution treatment, the sintered compacts were quenched, the...

example 2

[0048]Sintered magnets were produced in the same composition and by the same method as in Example 1. As in Example 1, magnets measuring 5×5×5 mm were cut from the resulting sintered magnets. A 20 μm layer of copper was electroplated onto the resulting magnets under the same conditions as in Example 1. The plated magnets were heat treated at 550° C. for 12 hours in a vacuum (oxygen partial pressure, 1×10−2 Pa), then slowly cooled to room temperature and subsequently coated by spraying on an epoxy resin, yielding hydrogen gas test specimens. The magnetic properties of the test specimens were measured with a VSM. The hydrogen gas test specimens were subjected to a hydrogen gas test under the same conditions as in Example 1, then removed from the pressure vessel. Following removal, the appearance of the magnets was visually checked and their magnetic properties were measured with a VSM.

example 3

[0057]A Sm2Co17-based magnet alloy was produced by formulating a starting material containing 18.0 wt % of samarium, 7.0 wt % of cesium, 14.0 wt % of iron, 4.5 wt % of copper and 2.5 wt % of zirconium, with the balance being cobalt. The starting material was placed in an alumina crucible and melted in an induction melting furnace under an argon atmosphere, then cast in a mold.

[0058]The resulting Sm2Co17-based magnet alloy was reduced to a size of about 500 μm or less with a jaw crusher and a Braun mill, after which it was milled to an average particle size of about 5 μm with a jet mill using a stream of nitrogen. The milled powder was molded with a magnetic field-generating press under a pressure of 1.5 t / cm2 within a magnetic field of 15 kOe. The resulting powder compacts were sintered in a heat treatment furnace under an argon atmosphere at 1170° C. for 2 hours, then solution-treated in argon at 1155° C. for 1 hour. Following the completion of solution treatment, the sintered comp...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

PropertyMeasurementUnit
wt %aaaaaaaaaa
wt %aaaaaaaaaa
thicknessaaaaaaaaaa
Login to View More

Abstract

Hydrogen embrittlement is prevented in Sm2Co17-based magnets and R2Fe14B-based magnets by metal plating the magnet, then carrying out heat treatment, or by forming a metal oxide or metal nitride layer on the metal plating layer or directly on the magnet itself.

Description

TECHNICAL FIELD[0001]The present invention relates to rare-earth sintered magnets which can be used in devices such as motors exposed for a long period of time to a hydrogen atmosphere. The invention also relates to a method of manufacturing such magnets.BACKGROUND ART[0002]Intermetallic compounds of rare-earth elements and transition metals have an ability to allow hydrogen to infiltrate into their crystal lattice, that is, the ability to store and release hydrogen in and out of the alloy. This property is employed in a variety of applications, such as hydrogen cells that make use of hydrogen storage alloys as typified by LaNi5. In rare-earth sintered magnet-related applications, the same property is used as a size reduction method for R2Fe14B-based alloys, and in the hydrogenation disproportionation desorption recombination (HDDR) process for producing R2Fe14B-based bonded magnets (JP-A 3-129702).[0003]However, hydrogen storage and release in an alloy or magnet causes hydrogen emb...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Patents(United States)
IPC IPC(8): H01F1/053H01F1/055H01F1/057H01F41/02
CPCH01F1/0557H01F41/026H01F1/0577
Inventor SAKAKI, KAZUAKIKASASHIMA, MASAKIHAMADA, RYUJIMINOWA, TAKEHISA
Owner SHIN ETSU CHEM IND CO LTD
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Patsnap Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Patsnap Eureka Blog
Learn More
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com